New paleomagnetic and geochronologic results from the eastern Tethyan Himalaya refine the size of Greater India in the Early Cretaceous

Abstract

Knowledge of the original size of Greater India in the Early Cretaceous is critical for Late Mesozoic East Gondwana reconstructions. However, estimates of Greater India extent have significant discrepancies in the Early Cretaceous. Here we report geochronologic and paleomagnetic studies on rocks of the Jiabula Formation in the northern subzone of the Tethyan Himalaya. The studied limestones are characterized by two-component magnetizations carried by detrital magnetite, which retains a primary remanence. Correspondingly, the high temperature magnetization components (350−525 °C) are isolated from 204 specimens using high-resolution thermal demagnetization. The new paleomagnetic data provide, after inclination shallowing estimation, an Early Cretaceous paleopole of 11.2°N/300.5°E, A₉₅ = 2.6°, which places the eastern part of the Tethyan Himalaya at a paleolatitude of 40.9° ± 2.6°S at ca. 126 Ma. Comparison of the new observed paleolatitude with the expected paleolatitude (49.7° ± 2.8°S) of India implies that Greater India had an extension of 968±418 km (8.8° ± 3.8°) at ca. 126 Ma. Integrating the new results with our previous Campanian results (ca. 75 Ma), we conclude that Greater India had a comparable extension of ∼900 km during ca. 126−75 Ma. The improved estimate of the dimensions of Greater India leads to an updated reconstruction of paleogeography in the Early Cretaceous.